Rotary hearth oven



June 17, 1930. BARTUNG 1,765,196

ROTARY HEARTH OVEN Filed June .27, 1927 1 4 Sheecs--SheerI l gu lr7-06M/Ews June 17, 1930. PPPPPPPP NG 1,765,196

RoT-

June 17, 1930. F. BARTLING j 1,765,196

ROTARY HEARTH OVEN A fm A Fly. 3

June 17, 1930. F. BARTLING 1,765,196

ROTARY HEARTH OVEN Filed June 27, 1927 4 Sheets-Sheet 4 Patented` June17, 1930 FRIEDRICH BARTLING, F MUNICH, GERMAY ROTARY HEARTH OVENApplication filed June 27, 1927,

rI`his invention relates to ovens of the rotary annular hearth type.For' the purpose of the present invention this type of oven may bemoreparticularly 'defined as anl oven adapted for continuous operationand wherein the chamber for the material to be heat treated has the formof an annular Channel closed at the top and open at the bottom. Theopening at the bottom of this annular channel is closed by acontinuously rotating annular hearth, the so-called rotary plate. Thematerial for treatment is distributed in ya uniform layer on this hearthplate andy carried thereby from the charging i5 locality, through theoven chamber, to the place where discharge of the material is effected.In this manner'heat treatment of the material is carried koutin the overchamber. The oven is generally heated indirectly by separate externalheating means, the koven gases (for instance, vapors, or gases resultingfrom distillation yof the material or otherwise arising) being carriedoff through special separate ducts provided for this purpose. Betweenthe stationary oven walls and the rotating hearth plate it is necessaryto yprovide special gastight sealing means. The hearth plate is usuallyrotated through the agency of suitable ksupporting and driving'devicesarranged beneath it.

yA particularly-effective method of heating in ovens ofv this kind isobviously the direct heating of the working hearth from below but thismethod is fraught with ydifliculties owing to the fact that the hearthis maintained in continuous rotation. In the first place this method ofheating requires that the space under the rotating hearth plate be keptas free as possible-'from supporting and driving means. Yet even if thisbe done, gases (as has been almost universaly hitherto) isunsatisfactory, since the heat imparted 5 to the travelling hearth platevaries irregularly as betweendifl'erent parts of said plate -andfluctuates in intensity. In particular when the material to betreatedris spread out on the working hearth in an,` extremely thin layer, as isalways the practice of the lheating bymeans of currents of hot presentinventor accompanied by Serial No. 201,953, and in Germany January 15,1927.

s such irregular heating is, disastrous results.

Having regard to these difficulties, the' fundamental idea of thepresent invention consists in using, for they underneath heating of therevolving hearth in rotary annular hearth plate ovens, the so-calledflameless combustion, also known by the names of surface or contactcombustion. l It is known that this type of combustion is based on theprovision of a porous ireproof contact mass, or radiant body, which isfed through burners with combustible gases, which raise the mass toincandescence, whereby the combustible gas is burned without theformation ofV any flame but with the evolution of av great amount ofheat.

In the practical application of`r this idea,r according to the presentinvention, the space beneath the annular rotating hearth ,is filled upvwith a radiant body which can be heated by the method of ilamelesscombustion.v r

In conjunction with various arrangements of ovens proposed by thepresent inventors,

the new heating meanscan be applied in several dierent ways.

In a preferred arrangementthe radiant body is placed in a stationaryannular channel under the rotatinghearth plate. This may be accomplishedby filling the walled annularl'channel, intowhich the burnerl nozzlesopen at intervals, with a loose mass, such.

as pieces of fire clay, for example, which i suitablefor flamelesslcombustion. f

When this arrangement 1s a dopted the.

supporting and driving means cannot of course be accommodated in thespace underneath the rotating hearth, as they normally tre.

A further feature of the invention con.-

sists,

therefore, in a novel arrangement of underneath.

According to this feature,l1the hearth platev is provided at each sidewith sions or outriggers projecting lateral extenradially from it andserving yto space it suitably from the supporting and driving meansproper', which ico Ver, irregularitiesoccur in itself may-be made hat,in the usual way,

but inrovens of this kind, in which the heat proceeds exclusively* frombelow, through the hearth plate, it is found that the latter,- beingsubject to irregular Land fluctuating heat intensities, has atendency tobe'comedis torted or warped. Such changes in the original shape of thisannular plate have very inconvenient results, both as' regardsthekeeping'ofthe joints between the interior of the Voven and the rotatingplate gastightfand also in respect of maintaining regular working of thesaid plate; An annular hearth plate, when warped in this manner, sets upknock ing iii the course of its rotary movement, so that, when anvattempt is made to distrib! ute the material to be treated on to theworking surface ofthe hearth in a very thin layyth'e'thicl'fness of thesaid layer which greatlyimpede the working of the oven andpreventuniform treatment of the material.' p

V'In one preferred constructional form of oven according to thisinvention the above named defect is overcome by giving tothe annularVhearth plate an'upwardly"arched or vaulted 'cross sectionfconforming, ifdesired, to the Larc'of a circle or toany-sinii-- lar symmetrical curve.'i

At thel same time the underside of the hearth plate is preferablyprovided with a network of stiffeningribs.l

VWhen pulverulentmaterial is to be ois-y tributed in a very vthin,layerI onthis hearth plate, it "is advantageousto break up orrough'en'its working surface', as by means ofjgroovesfurrows, ribs,humps tor the like, adaptedy to entrain the materialunderftreatthroi'ighftliefoven. .v

The advantages of yusing arched" hearth plates in rotary annular hearthplate ovens" resi-de firstly, inthe great/stability ofsuch plates,secondly in the more ehlicient'trans- Vment, for the betterl transportof lthe same Y ference lof heatwachieved (by their Yuse and,

A plate, besides thirdly, `ina better compensation ofthe ei:- pansionand distortion arising through fluc-` tuations of temperature. Thesystemoffribs" providedv onv the "underside of the hearth, serving vtostrengthen the same butalsoensures more efhcient transference of heatftothe fu' per surface'thereof and t compensates temperature uctuations byreason of the storing up of radiant heat in the said system of ribs.Thus a uniform temperature is ensured over the whole of the uppersurface of the hearth plate and the material to be heated is everywherepenetrated uniformly by the heat.

According to the present invention the hearth is supported by annularbox girders which are arranged on each side thereof and supported onseparate roller blocks running on an endless line of rails. In thesegirders may be incorporated devices such as sand gutters, which provide.a gastight seal between the Voven and the heating chamber and alsobetween the oven and the outer atmosphere.

As it is "of paramountimportance that the hearth plate proper, which issubjected to fairly strong and fluctuating heating action, be able toexpand and contract freely, without being prevented from so doing by thesupporting structure, the invention provides forthe insertion of linkmembers between the annular carriers andthe roller blocks, on the onehand Vand between the annular carriers and the supporting arms of thehearth, on the other. This yielding ar rangement may convenientlybecompleted by providing for mutual radial movability as between thesupporting arms andl the annular carriers. Y Y

In another arrangement vof rotating hearth designed by the inventors,the rotary plate is divided into two superimposed annular membersconnected by supporting means', the lower member, which closes in theoven` chamber, carrying sealing, supporting and driving means, while theupper' one, which carries the spread out layer 0f ioo material to betreated, is spaced at such ay distance above the lower plate within theoven chamber that it can be heated from.

below. In this kind of hearth the space between the working plate andthe'support# ingl plate may, according to the invention, be used for theaccoininodationof a radiant body which then partakes of the rotarymovement ofthe hearth itself. p diant body cannot, ot course, consist ofloose material but may, in accordancewith this invention, consist of agrid structure of fire clay or equivalent l in which can be filled up-bya suitable loose mass.

This ra-`A materialf, thespaces The supply of the combustible gas maythen conveniently be effected by means of burner nozzles penetratingheSdewaus; n i

kof the furnace, y c y Various constructional formsof appa ratusvaccordingto the .present invention are` shown in they accompanyingdrawin0'sv infV Figures l and 2 lshow the generalarrange-Y ment ofvthe'newoven invertical axial sec-V ion and in plan view, respectively. Y

igure lafshow's a somewhat modiiedconstructionalform of thehearth*plate.'y

a sliding Y shoe 11.

, vFigure 3 illustrates another` constructional form of the radiant bodyand' hearth substantially in `vertical section on line 3-3 vof Fig. 4;

Figure 4 is a F'g. 3. l. y,

ln the constructions illustrated, the work-` ing hearth proper,designated by the numeral .1, separates the annular oven chamber 2`fromthe Aheating channel 3 which is likewise annular.

In the example of yconstruction shown in Figures 1 and 2 the supportingand driving means are arranged on both sides of the hearth plate and jutout sideways therefrom. The space underneath. the vworking hearth istherefore perfectly free and it is used to form a spacious` heating.channel 3, which, according to the present invention, is lled with aloose mass. This loose mass consists of the materials usually employedfor iiameless combustion, ,whichA materials must be iireproof'and porousand must presenta rough external surface.

`Heating is effected by burner nozzles 25 distributed at'intervalsaround the circumference of the oven and supplying the conibustiblegasto theheating channel from below.

rill-he annular hearth section on the. line 4-4 of plate 1 'is archedrinthe construction shown in Figure 1 so that ythe inner and outer edges ofthe annular .hearth are lower than yits crown line and flat in theconstruction shown in Figure la, and in both cases has its walls as thinas possible. On its underside it is provided with a network ofstitfening ribs 4, while .its upper surface, if pulverized or' dustymaterial is to be treated, may be roughened, asv

by furnishing it withribs, grooves, furrows, humps or the like, whichentrain the material and act as carriers therefor'. The heated Amaterialgives ofi' gaseous products, which lcan escape through branches in thetop of the oven or be drawn off. The material Hows on to the annularhearth 'through a delivery apparatus 6, which, however, forms no part ofthe present invention, while the completely treated material isgenerally drawn offr from the hearth plate by suction means.

According tothe present invention radially projecting extensions oroutriggers 7 are affixed to the working vhearth and these protrude intoan annular-,space arched over by the top of the oven 21 and lyingoutside the'range of inlluence of the heating channel 3. ...Each of theoutriggers terminates ina ball pan 8 which is supported on a large steelball or a hemispherical bearing 9. The

steel ball itself rests onA orv in a hemispheri'v cal bearing surface orsocket 10, formed in lf the bearings 9 are suitable Y supports :siy

constructed as hemispherical bearings, the

half balls which act as substitutes for the f furnished on both sideswith lugs orflanges between which the sliding shoes 11 can moveradially. The side walls of the box girders form, together' with outerandl inner walls 15 and 16,'sand gutters `which act as seals between theoven chamber 2, the outer -air' on the one hand and the heating channelon the other. Another sand gutter 161 may be providedy to act as a sealbetween the heating ,chamber and the outer air. yEach .annular boxgirder 13 is carried by a number of rollerblocks 17 which run on endlesslines of rails 18. The roller blocks carry for driving purposes acircular rack 19 which is kept in rotation. by a driving pinion 20.Between each roller block 17 and the box girder 13 is interposed a pivotmember 22, which permits Vof mutual oscillatory adjust ment as betweenthe box girders and the rollers. n

lln the constructional form shown in FiguresB and 4 the rotaryhearthstructure rotates in thek annular oven chamber 51. This rotary hearthstructure comprises two superposed plates, namely, the working or hearthplate r53 and the supporting plate 54. The supporting plate ismounted onthe bearer 55 with theV travelling frame' and also` the sealing members57. By means of on which the materialto be treated is spread out, Visheld above lthe supporting plate 54. Around the ovenchamber 51, betweenthe treatment chamber rproper andthe space be* tween the plates and' 54,additional seals 58 the working p'late,

59 may be inserted, particularly when theV material under treatmenthas'toV be distilled, inwhich case it is desirable to obtain thegases'resulting from distillation in as purev a state as possible. y v

The passage-like chamber between the plates 53. and 54 is filled,according to this invention, by a light .grid structure l(50,'of fireclay or other iireproof and porous lmaterial. The radiant bodies soformedfparf. take of the rotary movement of the hearth izoy andmusttherefore be made las light as possible. The combustible gas issupplied by. oneor more burner jetsrl, and the products ofcombustion'maybe carried away through apipe62. 1. y Y.

Claims; i 1.'A'rotary vannular hearth; oven com@ i Vupwardly arched incross `said furnace space, and

' formly by successiv havin(r hemispherical to s bearino' A l b vsaidextensions to lrest'on said hemispheriprising an annular oven chamber,an annular Working hearth plate rotatable in said chamber, said annularhearth plate .being upwardly arched in'cross section, said chamberhaving a furnace space beneath the ana radiant body in means fixed tothe chamber Walls to supply combustible gas to said 'body for flamelesscombustion therein whereby the parts of the roasting hearth are heateduniformly by successively passnular Working hearth,

Y ing said means.

l 2. A rotary annular hearth oven comprisy ing an annular oven chamber,an annular Working hearth plate rotatable in said chamber, said annularhearth plate being section, said chamber having an annular furnacespace'beneathand concentric with the annular Working hearth, a. rdiantbody in said furnace Vspace comprising' a loose mass of refractorymaterial suitable for flameless,'combustion, said mass extending)`upwardinto therai'ch of the he rth plate, and a pluralityxof 'burnernozzles fixed in position with rewith and mounted at each vside of saidan-V nular hearth, 'bearing`v` members movable radially on saidsi'ipporting surfacesand cal bearings andthereby support said hearth,means tov cause said surfaces to move concentrically ivithrthe hearth,and a furnace beneath'said Working` hearth. l. A rotary annular hearth'-according toy claim 7, 'in which a plurality of bearing members areprovided havingV flat bottoms slidable along said surfaces, and bearingpans on said extensions to rest on said heini* spherical bearings andthereby support said hearth, Vannular tracks disposed concentric I withsaid annular -hearthat each side tlieref of,meanstraveling onsaidf-tracks and supporting said extensions and including pivotalconnections having axes at a'right angle tothe respective radii ofthe'annular hearth, and afurnace beneath said Workingrhearth. f5. YArotary annular hearth oven-comprisingang annular oven chamber, Vanannularl Workinghearth rotatable in said chamber,

annular tracks concentric With andV on each sideV of`lsaidlannular-hearth,` an annular are heated uni- Y pans on girderarrangedjabove each of said tracks,

Yroller blocks traveling on the tracksl andI supporting ual pivotsbetween blocks and the said jectingl from said the respective girders,individthe respective roller girder, and means prohearth and carriedAbyV saidgirders to support said hearth withoutV aV radiant body in saidfurnace space, meansYV fixed to the chamber Walls to supply combustiblegas to'said body for llamelesslco'm- Y bustion therein whereby the partsof the rotating hearth plate are heated uniformly by successivelypassing said means, annular supports for the Vannular hearthfplate ateach side thereof, and seals comprising cooperating members mounted onsaid hearth, said Vfurnace chamber and said supports whereby to preventthe passageV of gas'from the furnace space to the atmosphere or to theupper surface of said hearth plate, and 'f e passage of gas from theupper surface or said hearth plate to the atmosphere. t

ln testimony whereof I Vhave ,signedV my name to this specification. v Y

rrtinnnion BARKTLL'NG.,

